A new type of "Sensor" physics object is available in the GE for advanced
collision management. It's called Sensor for its similarities with the
physics objects that underlie the Near and Radar sensors.
Like the Near and Radar object it is:
- static and ghost
- invisible by default
- always active to ensure correct collision detection
- capable of detecting both static and dynamic objects
- ignoring collision with their parent
- capable of broadphase filtering based on:
* Actor option: the collisioning object must have the Actor flag set to be detected
* property/material: as specified in the collision sensors attached to it
Broadphase filtering is important for performance reason: the collision points
will be computed only for the objects that pass the broahphase filter.
- automatically removed from the simulation when no collision sensor is active on it
Unlike the Near and Radar object it can:
- take any shape, including triangle mesh
- be made visible for debugging (just use the Visible actuator)
- have multiple collision sensors using it
Other than that, the sensor objects are ordinary objects. You can move them
freely or parent them. When parented to a dynamic object, they can provide
advanced collision control to this object.
The type of collision capability depends on the shape:
- box, sphere, cylinder, cone, convex hull provide volume detection.
- triangle mesh provides surface detection but you can give some volume
to the suface by increasing the margin in the Advanced Settings panel.
The margin applies on both sides of the surface.
Performance tip:
- Sensor objects perform better than Near and Radar: they do less synchronizations
because of the Scenegraph optimizations and they can have multiple collision sensors
on them (with different property filtering for example).
- Always prefer simple shape (box, sphere) to complex shape whenever possible.
- Always use broadphase filtering (avoid collision sensor with empty propery/material)
- Use collision sensor only when you need them. When no collision sensor is active
on the sensor object, it is removed from the simulation and consume no CPU.
Known limitations:
- When running Blender in debug mode, you will see one warning line of the console:
"warning btCollisionDispatcher::needsCollision: static-static collision!"
In release mode this message is not printed.
- Collision margin has no effect on sphere, cone and cylinder shape.
Other performance improvements:
- Remove unnecessary interpolation for Near and Radar objects and by extension
sensor objects.
- Use direct matrix copy instead of quaternion to synchronize orientation.
Other bug fix:
- Fix Near/Radar position error on newly activated objects. This was causing
several detection problems in YoFrankie
- Fix margin not passed correctly to gImpact shape.
- Disable force/velocity actions on static objects
This commit completes the support for modifiers in the BGE.
- The physic shape is generated according to the derived mesh.
This is true for all types of shapes and all types of
objects except soft body.
- Optimization for static derived mesh (mesh with modifiers
but no armature and no shape keys). Replicas will share
the derived mesh and the display list: less memory and
faster rendering. With this optimization, the static
derived mesh will render as fast as if the modifiers were
applied.
Known Limits:
- Sharing of mesh and display list is only possible between
in-game replicas or dupligroup. If you want to instantiate
multiple objects with modifiers, use dupligroup to ensure
best memory and GPU utilization.
- rayCast() will interact with the derived mesh as follow:
Hit position and hit normal are the real values according
to the derived mesh but the KX_PolyProxy object refers to
the original mesh. You should use it only to retrieve the
material.
- Dynamic derived mesh have very poor performance:
They use direct openGL calls for rendering (no support
for display list and vertex array) and they dont't share
the derived mesh memory. Always apply modifiers on dynamic
mesh for best performance.
- Time dependent modifiers are not supported.
- Modifiers are not supported for Bullet soft body.
add -nojoystick commandline option: it takes 5 seconds everytime to start the game engine, while there IS no joystick.
In other words: blender -noaudio -nojoystick improves workflow turnaround times for P - ESC from 7 seconds to 1 second!
Improved Bullet soft body advanced options, still work-in-progress. Make sure to create game Bullet soft bodies from scratch, it is not compatible with last weeks builds.
The Physics button controls the creation of a physics representation
of the object when starting the game. If the button is not selected,
the object is a pure graphical object with no physics representation
and all the other physics buttons are hidden.
Selecting this button gives access to the usual physics buttons.
The physics button is enabled by default to match previous Blender
behavior.
The margin parameter allows to control the collision margin from
the UI. Previously, this parameter was only accessible through
Python. By default, the collision margin is set to 0.0 on static
objects and 0.06 on dynamic objects.
To maintain compatibility with older games, the collision margin
is set to 0.06 on all objects when loading older blend file.
Note about the collision algorithms in Bullet 2.71
--------------------------------------------------
Bullet 2.71 handles the collision margin differently than Bullet 2.53
(the previous Bullet version in Blender). The collision margin is
now kept "inside" the object for box, sphere and cylinder bound
shapes. This means that two objects bound to any of these shape will
come in close contact when colliding.
The static mesh, convex hull and cone shapes still have their
collision margin "outside" the object, which leaves a space of 1
or 2 times the collision margin between objects.
The situation with Bullet 2.53 was more complicated, generally
leading to more space between objects, except for box-box collisions.
This means that running a old game under Bullet 2.71 may cause
visual problems, especially if the objects are small. You can fix
these problems by changing some visual aspect of the objects:
center, shape, size, position of children, etc.
So for the 2.4 release, both bullet AND sumo will be enabled. You can choose in the world buttons which physics engine is active for a scene.
sorry if this breaks your builds!
added raycast support for bullet (no triangle-mesh support, soon)
added python methods for 'getHitObject', getRayDirection, getHitPosition and getHitNormal for mouse over sensor,
which makes it easy for a shootout.blend demo :)
>e.g. my msvc6 and gcc in linux. right?
>BM
thanks bjornmose, is was a typo
(it only disabled bullet for Visual Studio 2006, which is not even in planning stage :)
Should be fixed now
[SCons] Build with Solid as default when enabling the gameengine in the build process
[SCons] Build solid and qhull from the extern directory and link statically against them
That was about it.
There are a few things that needs double checking:
* Makefiles
* Projectfiles
* All the other systems than Linux and Windows on which the build (with scons) has been successfully tested.
(adding)
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
also the Makefile.in's were from previous patch adding
the system depend stuff to configure.ac
Kent
--
mein@cs.umn.edu